Perovskite materials - Page 6

Scientists from Dresden University of Technology (TU Dresden), AMOLF, Helmholtz-Zentrum Dresden Rossendorf and Johannes Gutenberg University Mainz have transformed single-cell algae into functional perovskite materials. The team, led by scientists at the B CUBE—Center for Molecular Bioengineering at TU Dresden, converted mineral shells of algae into lead halide perovskites with tunable physical properties. The new perovskites have unique nano-architectures that are said to be unachievable by conventional synthetic production.

The method can be applied to the mass production of perovskites with tunable structural and electro-optical properties from single-celled organisms. 

Researchers from Penn State and the U.S. Army Combat Capabilities Development Command Aviation & Missile Center have created a new process to fabricate large perovskite devices that is more cost- and time-effective than previously possible and that might accelerate future materials discovery.

“This method we developed allows us to easily create very large bulk samples within several minutes, rather than days or weeks using traditional methods,” said Luyao Zheng, a postdoctoral researcher in the Department of Materials Science at Penn State and lead author on the study. “And our materials are high quality — their properties can compete with single-crystal perovskites.”

A research team from City University of Hong Kong (CityU), Curtin University, National Taiwan University, Huazhong University of Science and Technology, Nankai University and Polish Academy of Sciences recently developed a lead-free perovskite photocatalyst that delivers highly efficient solar energy-to-hydrogen conversion.

The team unveiled the interfacial dynamics of solid-solid (between halide perovskite molecules) and solid-liquid (between a halide perovskite and an electrolyte) interfaces during photoelectrochemical hydrogen production. The latest findings open up an avenue to develop a more efficient solar-driven method for producing hydrogen fuel in the future.

Researchers from the University of Minnesota Twin Cities-led, University of Wisconsin–Madison and Pacific Northwest National Laboratory have developed a new method for making thin films of perovskite oxide semiconductors, a class of “smart” materials with unique properties that can change in response to stimuli like light, magnetic fields, or electric fields. 

Their work could allow researchers to harness these properties and even combine them with other emerging nano-scale materials to make better devices such as sensors, smart textiles, and flexible electronics.

Researchers from South-Africa's University of the Western Cape, University of Missouri and Argonne National Laboratory have developed a new way of enhancing the stability and performance of perovskites. 

Missouri University professor Suchismita (Suchi) Guha, the lead author of the study, and her collaborators improved the methods for making lead halide perovskites. Previous techniques for making these thin-film perovskites required liquid processing using solvents, which rendered the films susceptible to degradation when exposed to air. Additionally, with  prior manufacturing processes, one of its molecules undergoes a change to its structure, causing performance limitations in real-world operating conditions. 
With the new technique, the researchers were able to prevent the change, holding the affected molecule in a stable structure throughout a large temperature range. Additionally, the new technique rendered the perovskite air stable, making it appropriate for a potential solar cell. 

This is a sponsored post by MBRAUN

The potential of perovskites

Over the past decade, perovskites solar cells have attracted tremendous interest from the academic community, becoming a leading photovoltaic trend. Advances in the fundamental understanding of perovskites’ chemical and physical processes made them an attractive class of material for many researchers. In parallel, engineering developments on the architecture and fabrication methods of perovskite-based solar cells are becoming increasingly interesting for the PV industry.

Processing of perovskites

In general, three main types of perovskites processes can be distinguished – the fully vacuum-processed, the fully ambient processed and the hybrid type. For each process, MBRAUN can offer dedicated equipment solutions which will be showed in outline in the following paragraphs.

On one hand vacuum-based methods convince due to high-quality thin films, leading to the best device performance but are but are also characterized by comparatively high investment and operating costs. On the other hand, solution-processing techniques, like spin coating or slot-die coating also produce good-quality layers but excel at significantly lower investment and operation costs.

Comparison of wet and vacuum coating

An international research group, led by Dr. Yang Bin from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), has developed cadmium (Cd)-based perovskite single crystals with long afterglow and high luminous quantum yield, and investigated its afterglow luminescence dynamics mechanism.

Afterglow materials have the ability to store multiple radiations such as visible photons, ultraviolet rays, and X-rays. They are widely used in display, biological imaging, anti-counterfeiting technology, and data storage. However, traditional all-inorganic phosphors, such as oxide, sulfide, and nitride-based afterglow materials, have high lattice energy and usually need to be produced by high-temperature processing (>1000°C), which brings considerable energy consumption and safety risks to production and preparation.

In June 2021, Tokyo Chemical Industry Company Limited (TCI) started offering new hole selective self-assembled monolayer (SAM) forming agents, 2PACz [Product Number: C3663], MeO-2PACz [D5798] and Me-4PACz [M3359] for high performance perovskite solar cells and OPVs. Now, TCI has expanded its range of SAMs by adding two new high-efficiency materials: Me-2PACz [M3477] and Br-2PACz [B6391].

The SAM materials enable efficient, versatile and stable p-i-n perovskite solar cell devices. These materials are useful for tandem solar cells as they grant conformal coverage on rough textures. In fact, a perovskite solar cell that uses the SAM hole transport layer can realize more than 20% efficiency without using dopants or additives. Perovskite-Silicon tandem solar cells that use Me-4PACz as a hole contact material realized 29.15% efficiency. Costs are lowered thanks to extremely low material consumption, and the processing is very simple and scalable.

Researchers from the Department of Energy’s Ames National Laboratory and The University of Toledo have developed a new characterization tool that allowed them to gain unique insight into a perovskite material. Led by Ames' Jigang Wang, the team developed a microscope that uses terahertz waves to collect data on material samples. The team then used their microscope to explore Methylammonium Lead Iodide (MAPbI₃) perovskite.

Richard Kim, a scientist from Ames Lab, explained the two features that make the new scanning probe microscope unique. First, the microscope uses the terahertz range of electromagnetic frequencies to collect data on materials. This range is far below the visible light spectrum, falling between the infrared and microwave frequencies. Secondly, the terahertz light is shined through a sharp metallic tip that enhances the microscope’s capabilities toward nanometer length scales.

Researchers from Israel's Bar-Ilan University and Weizmann Inst. of Science have measured the effect of humidity on hardness and elastic modulus (E) for two series of lead halide perovskite single crystals. The results indicated the influence of hydrogen (H)-bonding, bond length, and polarization of the ions in lead halide perovskite single crystals.

The team detected an inverse relation between hardness and modulus, which was strengthened with increased humidity. Their findings shed light on the material's distinct structure and properties at the atomic scale. The conclusion of this work was based on the evaluation of outcomes of various nano-indentation techniques that differentiated between surface and bulk E and explored different manifestations of hardness.